Fabrication process of Al small Josephson junctions for quantum bits Mutsuo Hidaka and *Masaaki Maezawa International Superconductivity Technology Center *National Institute of Advanced Industrial Science and Technology December 14, 2011 General meeting of FIRST Quantum Information Processing Project Collaborators ISTEC: T. Satoh, S. Nagasawa, K. Hinode and Y. Kitagawa AIST: R. Noguchi, M. Yamagishi, T. Horikawa and H. Akinaga NTT: T. Maruyama
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Fabrication process of Al small Josephson … process of Al small Josephson junctions for quantum bits Mutsuo Hidaka and *Masaaki Maezawa International Superconductivity Technology
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Fabrication process of Al small Josephson junctions for quantum bits
Mutsuo Hidaka and *Masaaki Maezawa
International Superconductivity Technology Center *National Institute of Advanced Industrial Science and Technology
December 14, 2011 General meeting of FIRST Quantum Information Processing Project
Collaborators ISTEC: T. Satoh, S. Nagasawa, K. Hinode and Y. Kitagawa AIST: R. Noguchi, M. Yamagishi, T. Horikawa and H. Akinaga
NTT: T. Maruyama
Rough image of integrated Al Q-bit
Cross section structure of JJ (Josephson junction)
Al (Base electrode & Lower wiring)
AlOx (Tunnel barrier) Al (Counter electrode)
Al (Upper wiring)
SiO2
Au/Ti pad
Pd resister
Al co-planer signal line ( Upper-wiring layer)
Q-bit 1~100/chip
~1 µm
~100 nm
JJ 50 nm □~100 nm□
Readout SQUID
Control line
Nb (Resonator) Wafer size: 4 inch
EBL region
First step: fabrication of Al small (∼50 nm) Josephson junctions
Challenges
• Deposition of smooth and grain size controlled Al.
• Patterning of small JJs( ∼50 nm).
• Etching Al small JJs by Chlorine RIE.
• Contact formation between JJs and the counter electrode.
• Etc.
Contact Formation by using CMP = Exposure of Counter Electrode of JJ
01/late CAD data + Al/AlOx/Al films sent to SCR JJ: EB lithography + etching + cleaning 02/25 wafers sent to ISTEC 02/28-03/03 BAS: EB lithography + dev. 03/07 BAS etching + cleaning 03/07 SiO2 deposition 03/08 CMP 03/08 COU: Al deposition 03/09 alignment window: EB lithography + dev. + etching 03/11 cleaning 03/30 wafer sent to Maruyama-san NTT May COU: EB lithography + dev. + etching + cleaning dicing Characterization: I-V, SEM, (TEM)
Al JJ Process Ver. 1
Earthquake
Damage by the earthquake • Unplanned stop of machines • Mechanical damage to buildings/machines - some need repairing • Limited electricity supply - no air-conditioning in cleanrooms • Leakage in waste-water pipelines in Tsukuba Central area
Al JJ Process Ver. 1 CAD Pattern
5 mm 2.
5 m
m
JJ-1 chip JJ size (from left to right) 0.1 μm x 2 0.3 μm x 2 0.6 μm x 2 1.0 μm x 2 3.0 μm x2 0.2 μm x1 0.4 μm x1 0.8 μm x1 2.0 μm x1